Can sympy stats be used to solve problems like this one? https://stats.stackexchange.com/questions/583577/unconditional-variance-of-ar2-garch1-1
I would really like to see a worked out sympy solution!
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I would like to define the piecewise function below using the sympy module and then calculate a Fourier series for it.
Unfortunately I have no idea how exactly this works and have not found anything helpful on the internet.
Thanks in advance
piecewise function
I am trying to implement GJK alg, entirely in symbolic form with Sympy,
but I am not sure it is possible/computationally feasible.
Did anyone tried this?
While learning Python, I found the SymPy module, that is actually a entire computer algebra system (CAS) you can use to solve symbolic problems in mathemathics, like differential equations, polynomials et cetera. Now I'm learning Pharo, and I'd like to know if there's a way to do symbolic maths from within Pharo, something similar to SymPy.
There is a CAS in PolyMath, which is ported from CUIS, and there is Mathemagics
Let A be a positive definite matrix, and let A=L*L' be its cholesky factorization, where L is lower triangular.
Let A2 = A + alpha*x*x' be a rank-1 update of matrix A, where x is a vector of appropriate dimension and alpha is a scalar.
The Cholesky factor update is a procedure for obtaining the factorization A2=L2*L2' without calculating A2 first, which is useful to speed up computations in the case of such low-rank matrix updates.
I am using BLAS/LAPACK libraries for elementary algebra manipulations. I can calculate the Cholesky factorization of a positive definite matrix with the routine spptrf. However, I have been looking around and I have not been able to find a BLAS/LAPACK function which performs Cholesky factor updates. May it be that there is not function doing so?
Additionally: In this old post, the addition of such routine was discussed. However, it is a very old post (2013) and I have not been able of finding anything more recent.
There is no such function. You can look at this discussion we had on SciPy. I've made up a Python script that does the update with the relevant paper. You can make use of those information.
https://github.com/scipy/scipy/issues/8188
If you feel competitive and actually write the Fortran code for this, I would really appreciate if you can submit it to LAPACK repo as a PR https://github.com/Reference-LAPACK/lapack
The BLAS libraries on Netlib as you pointed out however I doubt it is on the site. If you are looking for code simply there is code here.
If you want it fast I'd just turn that code into Julia. There is a book I've never checked out which may have these in it. Also, note you cited a paper that the author wrote the code for. You could have simply contacted the author of the paper. His website appears to be here. There is a problem with that link though.
I'm trying to solve free fall equation and i dont understand what's the meaning of the error.
It’s exactly what it says on the tin: SymPy does not have an analytic solver for these kinds of differential equations implemented.